/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 * Copyright (C) Google Inc.
 */

#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>

#define NGX_HTTP_BRUNSLI_STATIC_OFF 0
#define NGX_HTTP_BRUNSLI_STATIC_ON 1
#define NGX_HTTP_BRUNSLI_STATIC_ALWAYS 2

typedef struct {
  ngx_uint_t enable;
} ngx_http_brunsli_static_conf_t;

static ngx_int_t ngx_http_brunsli_static_handler(ngx_http_request_t *r);

static ngx_int_t ngx_http_brunsli_ok(ngx_http_request_t *r);
static ngx_int_t ngx_http_brunsli_accept(ngx_str_t *ae);

static void *ngx_http_brunsli_static_create_conf(ngx_conf_t *cf);
static char *ngx_http_brunsli_static_merge_conf(ngx_conf_t *cf, void *parent,
                                                void *child);
static ngx_int_t ngx_http_brunsli_static_init(ngx_conf_t *cf);

static const ngx_str_t ngx_http_brunsli_mime_type = ngx_string("image/x-j");

static ngx_conf_enum_t ngx_http_brunsli_static[] = {
    {ngx_string("off"), NGX_HTTP_BRUNSLI_STATIC_OFF},
    {ngx_string("on"), NGX_HTTP_BRUNSLI_STATIC_ON},
    {ngx_string("always"), NGX_HTTP_BRUNSLI_STATIC_ALWAYS},
    {ngx_null_string, 0}};

static ngx_command_t ngx_http_brunsli_static_commands[] = {

    {ngx_string("brunsli_static"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF |
         NGX_CONF_TAKE1,
     ngx_conf_set_enum_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_brunsli_static_conf_t, enable),
     &ngx_http_brunsli_static},

    ngx_null_command};

ngx_http_module_t ngx_http_brunsli_static_module_ctx = {
    NULL,                         /* preconfiguration */
    ngx_http_brunsli_static_init, /* postconfiguration */

    NULL, /* create main configuration */
    NULL, /* init main configuration */

    NULL, /* create server configuration */
    NULL, /* merge server configuration */

    ngx_http_brunsli_static_create_conf, /* create location configuration */
    ngx_http_brunsli_static_merge_conf   /* merge location configuration */
};

ngx_module_t ngx_http_brunsli_static_module = {
    NGX_MODULE_V1,
    &ngx_http_brunsli_static_module_ctx, /* module context */
    ngx_http_brunsli_static_commands,    /* module directives */
    NGX_HTTP_MODULE,                     /* module type */
    NULL,                                /* init main process */
    NULL,                                /* init module */
    NULL,                                /* init process */
    NULL,                                /* init thread */
    NULL,                                /* exit thread */
    NULL,                                /* exit process */
    NULL,                                /* exit main process */
    NGX_MODULE_V1_PADDING};

static ngx_int_t ngx_http_brunsli_static_handler(ngx_http_request_t *r) {
  u_char *p;
  size_t root;
  ngx_str_t path;
  ngx_int_t rc;
  ngx_uint_t level;
  ngx_log_t *log;
  ngx_buf_t *b;
  ngx_chain_t out;
  ngx_table_elt_t *h;
  ngx_open_file_info_t of;
  ngx_http_core_loc_conf_t *clcf;
  ngx_http_brunsli_static_conf_t *bscf;

  if (!(r->method & (NGX_HTTP_GET | NGX_HTTP_HEAD))) {
    return NGX_DECLINED;
  }

  if (r->uri.data[r->uri.len - 1] == '/') {
    return NGX_DECLINED;
  }

  bscf = ngx_http_get_module_loc_conf(r, ngx_http_brunsli_static_module);

  if (bscf->enable == NGX_HTTP_BRUNSLI_STATIC_OFF) {
    return NGX_DECLINED;
  }

  if (bscf->enable == NGX_HTTP_BRUNSLI_STATIC_ON) {
    rc = ngx_http_brunsli_ok(r);

  } else { /* NGX_HTTP_BRUNSLI_STATIC_ALWAYS */
    rc = NGX_OK;
  }

  clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

  if (!clcf->gzip_vary && rc != NGX_OK) {
    return NGX_DECLINED;
  }

  log = r->connection->log;

  p = ngx_http_map_uri_to_path(r, &path, &root, sizeof(".j") - 1);
  if (p == NULL) {
    return NGX_HTTP_INTERNAL_SERVER_ERROR;
  }

  *p++ = '.';
  *p++ = 'j';
  *p = '\0';

  path.len = p - path.data;

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http filename: \"%s\"",
                 path.data);

  ngx_memzero(&of, sizeof(ngx_open_file_info_t));

  of.read_ahead = clcf->read_ahead;
  of.directio = clcf->directio;
  of.valid = clcf->open_file_cache_valid;
  of.min_uses = clcf->open_file_cache_min_uses;
  of.errors = clcf->open_file_cache_errors;
  of.events = clcf->open_file_cache_events;

  if (ngx_http_set_disable_symlinks(r, clcf, &path, &of) != NGX_OK) {
    return NGX_HTTP_INTERNAL_SERVER_ERROR;
  }

  if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool) !=
      NGX_OK) {
    switch (of.err) {
      case 0:
        return NGX_HTTP_INTERNAL_SERVER_ERROR;

      case NGX_ENOENT:
      case NGX_ENOTDIR:
      case NGX_ENAMETOOLONG:

        return NGX_DECLINED;

      case NGX_EACCES:
#if (NGX_HAVE_OPENAT)
      case NGX_EMLINK:
      case NGX_ELOOP:
#endif

        level = NGX_LOG_ERR;
        break;

      default:

        level = NGX_LOG_CRIT;
        break;
    }

    ngx_log_error(level, log, of.err, "%s \"%s\" failed", of.failed, path.data);

    return NGX_DECLINED;
  }

  if (bscf->enable == NGX_HTTP_BRUNSLI_STATIC_ON) {
    r->gzip_vary = 1;

    if (rc != NGX_OK) {
      return NGX_DECLINED;
    }
  }

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http static fd: %d", of.fd);

  if (of.is_dir) {
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, log, 0, "http dir");
    return NGX_DECLINED;
  }

#if !(NGX_WIN32) /* the not regular files are probably Unix specific */

  if (!of.is_file) {
    ngx_log_error(NGX_LOG_CRIT, log, 0, "\"%s\" is not a regular file",
                  path.data);

    return NGX_HTTP_NOT_FOUND;
  }

#endif

  r->root_tested = !r->error_page;

  rc = ngx_http_discard_request_body(r);

  if (rc != NGX_OK) {
    return rc;
  }

  log->action = "sending response to client";

  r->headers_out.status = NGX_HTTP_OK;
  r->headers_out.content_length_n = of.size;
  r->headers_out.last_modified_time = of.mtime;
  r->headers_out.content_type = ngx_http_brunsli_mime_type;

  if (ngx_http_set_etag(r) != NGX_OK) {
    return NGX_HTTP_INTERNAL_SERVER_ERROR;
  }

  h = ngx_list_push(&r->headers_out.headers);
  if (h == NULL) {
    return NGX_HTTP_INTERNAL_SERVER_ERROR;
  }

  h->hash = 1;
  ngx_str_set(&h->key, "Content-Encoding");
  ngx_str_set(&h->value, "identity");
  r->headers_out.content_encoding = h;

  /* we need to allocate all before the header would be sent */

  b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
  if (b == NULL) {
    return NGX_HTTP_INTERNAL_SERVER_ERROR;
  }

  b->file = ngx_pcalloc(r->pool, sizeof(ngx_file_t));
  if (b->file == NULL) {
    return NGX_HTTP_INTERNAL_SERVER_ERROR;
  }

  rc = ngx_http_send_header(r);

  if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
    return rc;
  }

  b->file_pos = 0;
  b->file_last = of.size;

  b->in_file = b->file_last ? 1 : 0;
  b->last_buf = (r == r->main) ? 1 : 0;
  b->last_in_chain = 1;

  b->file->fd = of.fd;
  b->file->name = path;
  b->file->log = log;
  b->file->directio = of.is_directio;

  out.buf = b;
  out.next = NULL;

  return ngx_http_output_filter(r, &out);
}

static ngx_int_t ngx_http_brunsli_ok(ngx_http_request_t *r) {
  ngx_table_elt_t *ae;

  if (r != r->main) {
    return NGX_DECLINED;
  }

  ae = r->headers_in.accept;
  if (ae == NULL) {
    return NGX_DECLINED;
  }

  if (ae->value.len < ngx_http_brunsli_mime_type.len) {
    return NGX_DECLINED;
  }

  if (ngx_http_brunsli_accept(&ae->value) != NGX_OK) {
    return NGX_DECLINED;
  }

  r->gzip_tested = 1;
  r->gzip_ok = 0;

  return NGX_OK;
}

static ngx_int_t ngx_http_brunsli_accept(ngx_str_t *ae) {
  u_char *p;

  p = ngx_strcasestrn(ae->data, (char *)ngx_http_brunsli_mime_type.data,
                      ngx_http_brunsli_mime_type.len);
  if (p == NULL) {
    return NGX_DECLINED;
  }

  if (p == ae->data || (*(p - 1) == ',' || *p == ';' || *(p - 1) == ' ')) {
    p += ngx_http_brunsli_mime_type.len;

    if (p == ae->data + ae->len || *p == ',' || *p == ';' || *p == ' ') {
      return NGX_OK;
    }
  }

  return NGX_DECLINED;
}

static void *ngx_http_brunsli_static_create_conf(ngx_conf_t *cf) {
  ngx_http_brunsli_static_conf_t *conf;

  conf = ngx_palloc(cf->pool, sizeof(ngx_http_brunsli_static_conf_t));
  if (conf == NULL) {
    return NULL;
  }

  conf->enable = NGX_CONF_UNSET_UINT;

  return conf;
}

static char *ngx_http_brunsli_static_merge_conf(ngx_conf_t *cf, void *parent,
                                                void *child) {
  ngx_http_brunsli_static_conf_t *prev = parent;
  ngx_http_brunsli_static_conf_t *conf = child;

  ngx_conf_merge_uint_value(conf->enable, prev->enable,
                            NGX_HTTP_BRUNSLI_STATIC_OFF);

  return NGX_CONF_OK;
}

static ngx_int_t ngx_http_brunsli_static_init(ngx_conf_t *cf) {
  ngx_http_handler_pt *h;
  ngx_http_core_main_conf_t *cmcf;

  cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);

  h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers);
  if (h == NULL) {
    return NGX_ERROR;
  }

  *h = ngx_http_brunsli_static_handler;

  return NGX_OK;
}
